Apparatus for determining the moisture content of gases



Jan. 10, 1933. R. G. GUTHRIE ET AL 1,894,172

APPARATUS FOR DETERMINING THE MOISTURE CONTENT OF GASES Filed NOV. 12. 1930 L58. F IVfllE F Raw/m; 0F fll rsfislvcs 71v DEGREES BETWEEN WET Pmwfl/c 0 51MB 4N0 fl/Pr 5045 7175/?10MET5R8 F007 (JP 0175 HEP/waivers I2 3 45 6 789 |0Hl2l5l4l5l6|7 0.000587 50 9s 87 8 74 6862 566044 5.9 as 28 22 /7 72 7 2 0.000628 94 89 84 7a 73 68 .58 55 49 4a 40 55 5/ 27 22 I8 jfyl Irwenfirs: @5876 G.Gzafkrzle and Oscar J M65607,

Patented Jan. 10, 1933 UNITED STATES PATENT OFFICE ROBERT G. G'UTHRIE AND OSCAR J. WILBOR, OF CHICAGO, ILLINOIS, ASSIGNORS TO PEOPLES GAS lBY-PRODUCTS CORPORATION, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS APPARATUS FOR DETERMINING THE MOISTURE CONTENT OF GASES Application filed November 12, 1930. Serial No. 495,274.

' This invention relates to an apparatus for determining the moisture content of gases, and is particularly adapted for determining the moisture content of a flowing current of gas.

In certain industries, such as that involving the use of combustible gas for the treatment of metals by heating, annealing, carburizing, etc., it is desirable to control the amount of moisture present in the gas. The present apparatus is designed to facilitate this work by determining the moisture content of the flowing current of gas on its way to the furnace or other device of employment.

One of the features of the present invention is the provision of means for maintaining the gas at a substantially uniform temperature during the testing.

Another feature of the invention is the provision of means for operating a wet bulb thermometer under standard conditions whereby a definite and accurate determination is made. i

' Still another object of the invention is to provide a structure in which the gas may flow through the testing apparatus at a suflicient head of pressure, and yet no difiiculties,

of operation are caused to arise by the presence of the pressure head of the gas.

An illustrative form of construction of a testing device according to this invention is set forth in the accompanying drawing, in which:

Figure 1 represents a vertical section through the testing device.

Figure 2 is a table indicating the quantity of water present per cubic foot of gas as determined by the readings of the thermometers.

In the drawing the casing 10 is a jacket containing a body of liquid 11 which preferably is water, and is replenished from time to time through an inlet 12, and by the outlet 13. The gas which is to be tested as to moisture content is admitted through a connecconduit 18 conducts the gas downward and ward the lower end of the latter. Near the upper end of the pipe 17 is a branch 20 leadlng to the gas outlet connection 21 from which it flows to the furnace or other point of use. A dry bulb thermometer 2:2 is inserted into the vertical pipe 16 with its bulb in the portion of the same which is immersed in the body 11 of liquid, and is sealed with respect to the upper end of this pipe 16 by a perforated stopper 23 to prevent the escape of gas from the pipe 16.

Similarly, a wet bulb thermometer 24 is f sealed with respect to the pipe 19 by the perfo- 60 rated stopper 25, and has its bulb supported adjacent the lower end of the branch pipe 18. This wet bulb is surrounded by a capillary body 26 which may be of wicking or 1 similar fabric.

The lower end of the pipe 19 projects through the bottom 27 of the casing and is connected to a three-way cook 28 having a water supply connection 29 and a side branch 30 with an upwardly bent end 31 which preferably is transparent and has the two marks 32, 33 thereon corresponding to minimum and normal water levels. The rotatable plug .34 of the three-way cock is adapted to establish communication between the water sup- 3O ply pipe 29 and the external reservoir and indicator 30, 31 and between this external reservoir and indicator and the vertical pipe 19. It will be noted that the pool of water in the lower end of the tube 19 which replen- 35 ishes the supply in the capillary fabric is maintained at definite temperature by the pool 11 of liquid in the jacket 10, and hence the evaporation rate of this liquid is standardized, and no separate correction for it is 99 required.

One feature of the present invention is the fact that the gas passes upwardly in the illustrated form of the device, in both the pipes 16 and 19 which are connected by the branch 18 to form an N-shaped conduit, in each vertical leg of which is located a thermometer.

In operation, the valve plug 34 is moved until awater level is established in the eX- 100 ternal gage 31, and then the water is admitted into the vertical pipe 19. \Vhen the plug 34 establishes communication between the age and the pipe 19, and the interior of the device is at normal or atmospheric pressure, the level inside and outside must be identical and hence a definite control of the rate of moistening of the wet bulb by the capillary fabric 26 results. The plug 34 is now turned until the vertical pipe 19 is shut off.

The gas valve 14a is opened and gas flows through the pipe 14 and the coil 15 and thereby is brought to the temperature of the body 11 of water. This gas then continues upwardly in pipe 16 and downwardly through the branch 18 and again upwardly in the pipe 19 and finally passes out at the outlet 21. The body of liquid has brought the gas to a uniform temperature and maintains it at this tem erature. This facilitates the operation of t e' device as by a control of the temperature of the water, the dry bulb readings may be made substantially uniform, and hence the determination of moisture requires merely a reading of the differential of temperature on the wet thermometer and a consultation of a table such as shown in Figure 2.

In the usual way, the gas brings the bulb of the dry thermometer to its own temperature, so that the dry thermometer indicates the temperature of the gas. Further, the wet thermometer is cooled corresponding to the quantity of water which is evaporated from wick 26 owing to the lack of saturation of the particular gas being tested.

Since the temperature of the body of liquid '11 may be controlled, it is possible to determine the degree of saturation of a gas at a given temperature, so that for example the gas may be tested at a temperature substantially corresponding to the dew point of the gas having the desired quantity of water vapor therein, whereby the addition of moisture from the capillary fabric 26 will bring the gas to the desired degree of humidity for later employment.

In the abbreviated table shown in Figure 2, it will be noted that when the dry and wet bulb thermometer readings are both 32 F. (i. e. the gas is saturated in water vapor), there are 0.000304 pounds of water vapor per cubic foot of gas; and hence if there is a difference in reading so that the dry bulb thermometer is 32 and the wet bulb thermometer 28, then the relative humidity value is 60, and the particular gas being tested contains 0.0001824 pounds of water vapor per cubic foot of gas. Further, if the dry ulb reading is 32 and the wet bulb reading 22, the differential is 10, representing a humidity value of 4, and a moisture content of 0.00001216 pounds-of water vapor per cubic foot of gas. Further, if the body of liquid is at a higher temperature so that the dry bulb thermometer has a reading of 50, while the differential in reading of the wet bulb thermometer is 7, the relative humidity value is 56 and there are 0.000333 pounds of water vapor per cubic foot of gas since saturation at this dry bulb temperature means the presence of 0.000587 pounds of water vapor per cubic foot of gas.

If it be sought to maintain 0.000182 pounds of water vapor in each cubic foot of gas, and the dry bulb thermometer reading is 60, then the differential of temperature in the web bulb thermometer must be 16 (i. e. 44 F.).

It is obvious that the invention is not limited solely to the form of construction shown, nor the employment of the device to the manner described: but that it may be constructed and employed in many ways within the scope ofthe appended claims.

Having thus described the invention, whatwe claim as new. and desire to secure by Letters Patent, is:

1. 'In a moisture determining apparatus for gases, a conduit for the gas, dry and wet bulb thermometers extending into said conduit, said conduit having a depending branch for containing a water supply for the wet thermometer, conduit means extending from said portion to the exterior and including an upwardly bent end constituting a age, a branch for supplying water, and a s ut off valve for selectively closin communication between said portion, sai supply branch and said gage.

2. In an apparatus for determining moisture content of gases, a casing for providing a water jacket, a gas conduit extendin through said casing, dry and wet bulb thermometers having their bulbs located in the conduit and extendin portion located beneath the wet bulb thermometer for holding a water supply for said wet thermometer within said casin means to admit water into said portion an including a shut off valve, and means for indicating the water level in said portion.

3. A moisture determining apparatus for gases including a casing for providing a water jacket, a vertically disposed N-shaped tube in said casing and constituting a gas conduit, means to admit gas into the lower end of one leg of the N-tube so that the gas to the exterior of; said casing, said con uit having a branch to the lower end of said other tube, a gas inlet at the lower end of said first tube, a gas outlet at the end of said second tube, dry and Wet bulb thermometers each located in one of said tubes, and a casing providing a water jacket around said tubes.

5. In a moisture determining apparatus for gases, a casing for providing a water jacket, a gas conduit passing through said casing and including a coil, a substantially vertical tube connected to said coil and ex tending upwardly therefrom and adapted to contain a dry bulb thermometer, a second tube adapted to contain a wet bulb thermometer, conduit means to pass gas from the upper end of said first tube into a point near the lower end of said second tube, a gas outlet from the upper end of said second tube; and means to introduce water into the lower end of said second tube.

In testimony whereof, we aflix our signatures.

ROBERT G. GUTHR-IE. QSCAR J. VVILBOR: 

